1. Field of the Invention
The present invention relates to a technique of visualizing focusing information of photographic images as display on a screen.
2. Related Art
Digital still cameras equipped with liquid crystal displays and camera-equipped cell phones have been widely spread and used as imaging devices. In these imaging devices, the user can check the focusing status, for example, the blur or the out-of-focus, of each taken image on the liquid crystal display. Various techniques have been proposed to enable accurate recognition of the focusing status.
For example, an image processing device disclosed in Japanese Patent Laid-Open Gazette No. 2005-309559 sums up the number of edges included in each specified area of an image and extracts and displays an image section corresponding to an area having a greatest number of edges as a check image. Another image processing device disclosed in Japanese Patent Laid-Open Gazette No. 2006-72660 processes image data by Fourier transform and performs a deterioration enhancement process for the image having a high frequency component of or below a preset rate.
These prior art image processing devices give certain levels of information for focus judgment but are not capable of accurately detecting the position of focus. A system for accurate recognition of a focusing status of an image including the position of focus is thus highly demanded.